Liquid dispenser



Dec. 3, 1968 D. F. CORSETTE 3,414,169

LIQUID'DISPENSER Filed Feb. 17, 1967 2 Sheets-Sheet 1 lNl/EA/TO/Z, 0006445 A (025E275 a/M flww Dec. 3, 1968 I Filed Feb. 17, 1967 D. F. CORSETTE LIQUID DISPENSER 2 Sheets-Sheet 2 //VVENTO/,

fiOUGL/JSE (02557715 5) i 1M, Mywa aka/5W United States Patent 3,414,169 LIQUID DISPENSER Douglas F. Corsette, Los Angeles, Calif., assignor, by

mesne assignments, to Diamond International Corporation, New York,-N.Y., a corporation of Delaware Filed Feb. 17, 1967, Ser. No. 616,847 5 Claims. (Cl. 222-321) ABSTRACT OF THE DISCLOSURE A liquid dispensing pump including a plunger disposed for reciprocation in a cylinder through an annular collar which defines part of a breather passage at the upper end of the cylinder. The plunger rod and the collar jointly define a downwardly diverging annular valve seat around the plunger rod for wedging reception of an annular skirt of resiliently deformable material at the upper end of the piston, to close the breather passage. Also, the plunger rod and the piston have cooperating valve portions for alternately opening and closing a discharge passage through the plunger incident to plunger reciprocation.

This invention relates to improvements in a reciprocating liquid dispensing pump of the type such as is customarily fabricated of plastic materials for use with a portable liquid container. The liquid is discharged from the pump through a hollow reciprocating pump plunger and the pump includes venting and discharging valves, located externally and internally of the plunger respectively. These valves are automatically closed when the usual spring projected plunger is in its fully raised position to prevent leakage of fluid, either through the discharge passage or externally of the plunger and through the end of the pump cylinder. Such a pump is exemplified by the disclosures of United States Patent Nos. 3,159,316 and 3,228,571 to ODonnell et al., and -No. 3,187,960 to Gorman.

In a pump of the general class above described, it is necessary during operation of the pump to vent the container interior to the atmosphere in order to permit entry of air for the replacement of the withdawn liquid, as well as for pressure relief. Also, venting of the pump cylinder above the plunger piston is necessary in order to prevent the entrapment of fluid which might lock the piston against reciprocation. Normally the upper end portion of the cylinder communicates with the atmosphere through a plunger guide opening in the annular collar or cylinder head around the plunger rod, and the container interior in turn communicates with the atmosphere through an opening in the side wall of the cylinder.

It is highly desirable to prevent loss of the liquid contents of the container through the plunger guide opening, as for instance when the container with the pump applied thereto is being shipped or stored and subject to being wholly or partially inverted. For this purpose, it has been known to so position the vent or breather opening in the side wall of the cylinder that, when the plunger of the pump is projected to its fully raised position, it both covers the breather opening or vent and closes the guide opening in the cylinder head through which the plunger reciprocates to thus provide an external seal around the plunger. When thus positioned for cooperation with the plunger, it will be apparent that the location of the vent is in the pump chamber portion of the cylinder.

Also, it has been known to employ means for positioning the discharge valve to close the discharge passage through the plunger when the plunger is fully raised, to thus provide an internal seal within the plunger.

In order to secure a close fluid-tight engagement between the piston and the cylinder wall, it has become general practice to provide the piston with a depending skirt often of resilient elastic material provided with a relatively thin tapered skirt. Despite the necessity for venting means, the disposition of a vent or opening in the side wall portion of the pump cylinder, which must be traversed by the plunger position, has certain disadvantages. Specifically, the rather delicate peripheral edge of the piston skirt frequently has been subjected to damage by engagement with the inner edge of such a breather opening of the cylinder as it is moved downwardly across such opening during assembly and/or operation of the pump. Further, such disposition of the breather opening or vent in the operative or pump chamber portion of the cylinder wall may result in entrapment of the liquid in the upper end portion of the cylinder incident to upward movement of the piston beyond the opening, with the result that the entrapped liquid is forced upwardly through the guide opening around the plunger rod.

In order to avoid these disadvantages, the present invention envisions a pump structure having a venting means so arranged that the entire cylindrical inner wall of the pump chamber portion of the cylinder may be imperforate and smooth throughout its entire length to avoid the possibility of damage to the piston skirt. Further, to avoid entrapment of liquid above the piston, the pump cylinder above the piston communicates freely with the vent opening or passages in all positions of the piston to permit return to the container of any liquid above the piston.

The instant invention further comprises improvements in such a pump which employs a multi-functioning piston and valve of the type generally exemplified in the Gorman Patent No. 3,187,976, in which the piston is mounted for lost motion on the tubular plunger rod and cooperates with the plunger rod to afford seals both internally and externally of the plunger rod for controlling the liquid discharge passage through the plunger and the guide opening in the cylinder end wall respectively.

More specifically, the present invention includes the concept of forming the external seal by affixing to the pump cylinder a collar which concentrically encircles and slidably receives a cylindrical portion of the plunger. This collar presents a first annular sealing surface directed radially inwardly toward, but spaced from, a second outwardly directed annular sealing surface provided by a cylindrical portion of the plunger rod. The piston in turn is formed 'with an upwardly presented annular skirt or portion concentric to the radially opposed and spaced sealing surfaces abovementioned. This upwardly presented skirt has radially inner and outer faces adapted for sealing engagement with the respective opposed first and second sealing surfaces. The cooperating sealing surfaces are all relatively shaped, disposed and positioned for snug sealing reception of the upwardly presented ski-rt between, and in snug sealing engagement with, the first and second sealing surfaces.

Preferably the upwardly directed piston skirt is arranged for Wedging or jamming reception between the radially opposed first and second sealing surfaces above mentioned.

An important aspect of the invention resides in achieving such a wedging or jamming engagement without unduly impeding the relative movement between the piston and plunger rod which is relied upon for achieving the valving function necessary for controlling the discharge passage through the plunger.

For this purpose, the upwardly directed skirt of the piston is made resiliently or elastically deformable and of an internal diameter such that its inner sealing surface normally is in light wiping engagement with the plunger rod and fully slidable thereon. The sealing surface afforded by the plunger rod, in turn, is of substantially "ice cylindrical conformation, though either or both of the cooperating sealing surfaces of the cylinder and the piston skirt may be tapered or coned in a manner to radially compress the sealing skirt into tight sealing engagement with the rod as the skirt moves axially upwardly into the fixed sealing surface of the cylinder.

Also, the invention envisions means operative during the plunger compression stroke when such sealing surfaces above mentioned are disengaged, for maintaining an effective seal between the plunger rod and the piston while offering minimum interference with the valving motion between the plunger rod and piston. The means thus referred to is arranged in a manner such that its sealing action and efficiency is increased by liquid pressure within the plunger discharge passage.

In the accompanying drawings in which there are shown preferred exemplifications of the invention:

FIGURE 1 is an axial cross-section of a reciprocating pump as applied to a container (shown fragmentarily), the pump plunger being shown in its fully raised or projected position;

FIGURE 2 is a view similar to FIGURE 1, but with certain parts broken away, and showing the various parts in the positions which they assume substantially at the end of the downward plunger stroke;

FIGURE 3 is an enlarged cross-section on the line 3--3 of FIGURE 2; and

FIGURE 4 is a view similar to FIGURE 1, showing a further embodiment of the invention, equipped with an overcap, and including certain additional features.

In the drawings and in the following detailed description of the invention, various parts are illustrated in their preferred forms and are described in detail. However, it is to be understood that such detailed illustrations and description are merely for purposes of exemplification, and that various of the parts of the pump may be modified or, in some instances, omitted without departing from the invention as defined in the appended claims.

Referring now in detail to the accompanying drawing, the pump therein illustrated comprises a pump cylinder C adapted for positioning within the dispensing opening or spout of a conventional liquid container, illustrated in broken lines in FIGURE 1. Disposed for reciprocation in the cylinder is a plunger P, which includes a sleeve-like piston and a tubular plunger rod 11. The downwardly directed outwardly flaring piston skirt 12 has its lower peripheral edge in snug wiping engagement with the inner wall of the cylinder. The piston 10 and the uniform diameter portion of the cylinder C in which it recipro cates jointly define a variable-volume pump chamber 13. The inlet port 14 of the cylinder, adjacent the lower end of the chamber, is controlled by a conventional check valve 15 to admit liquid into the pump chamber 13 on each upward or suction stroke of the plunger. The check valve 15 is seated over the port 14 on each downward or compression stroke of the plunger. Liquid is delivered to the port through a dip tube 16, the upper end portion of which is coupled to the cylinder for communication with the inlet port in usual manner, it being understood that the lower end of the dip tube (not shown) will normally extend to a location closely adjacent the bottom of the container.

The plunger defines a valve controlled discharge passage 18 which opens upwardly from the pump chamber 13 through the sleeve-like piston 10. A valve member 19 controls the discharge port 20, so that, on each plunger compression stroke, liquid moves upwardly through the port, thence through the tubular piston rod 11 and into a suitable discharge head 21 on the upper external end of the rod. The discharge head may be of any conventional type, being here shown as a spray head of known design, from the outlet orifice 22 of which the liquid is discharged in the form of a spray.

As is usual, the head 21 is formed to provide a downwardly directed socket 23, which receives the upper end of the plunger rod, and places theinterior of the spray head and its orifice 22 in communication with the discharge passage 18 through the tubular plunger. Also, the sprayhead is provided with an upwardly directed finger piece 24 by which the plunger is alternately depressed, by the application of finger pressure, and then permitted to rise on its upstroke, through the action of a spring 25, which is compressed in the pump chamber, between the plunger and the lower end of the cylinder.

The pump cylinder C of the present embodiment is encircled by a projecting flange 26 adapted to rest on the upper end of the container neck, and is adapted for support by said flange in the dispensing opening of the container. Projecting upwardly from the inner periphery of the flange 26 in radially spaced concentric relation to the cylinder C is a cylindrical wall 27 which extends through an opening 28 in the container closure 30. The container closure 30 is here exemplified by a conventional closure cap having an internally threaded skirt 31 by which the closure is secured on the container by engagement with the external threads of the container neck. The container closure cap 30 thus coacts with the flange 26 to secure the pump in operative relation to the container; and in so doing, the flange may function as a gasket between the closure and the end of the container neck.

It will be noted that the cylinder is supported concentrically within the encircling wall 27 by means of a spider 32. The flange 26, wall 27, and spider 32 all preferably constitute integral portions of the cylinder.

The upper end of the space surrounded by the annular wall 27 is closed by a cylinder head in the form of an annular or centrally apertured collar 33, the central guide opening 34 of which slidably receives and guides the tubular plunger rod 11 of the plunger P.

The collar 33 is provided with any suitable means for securing it in position on the wall 27, as for instance the depending inner sleeve 35 which is snap-fitted at 36 into the wall 27. The collar 33 also has .a depending outer sleeve 37 which overhangs the top wall of the container closure.

The collar 33 and wall 27 thus function as a housing, the hollow interior of which defines a breather compartment 38 which, in the instant embodiment, is located primarily above the closure 30 and into which the open upper end of the cylinder C projects. The interconnected parts 33 and 27 also function to secure the pump and the container closure 30 in their assembled condition, by re taining the top wall of the closure between the radial flange 26 and the depending collar skirt 37.

The upper end of the cylinder C terminates in spaced relation below the top wall of the collar 33 and communicates with the breather compartment 38 jointly defined by the members 27 and 33. The compartment 38 communicates with the container interior through the annular clearance space 40 between the cylinder and collar sleeve 35 and, thence, downwardly through the spider 32.

The collar preferably is formed with a dependent inner sleeve 41 concentric to its guide opening 34 and defining a radially enlarged cylindrical counterbore 42 having a downwardly diverging conical valve seat 43. It will be seen that the lower edge of the sleeve 41 extends into the conical pilot portion 48 of the cylinder but is spaced from the cylinder C to provide a passage 44 for establishing communication between the breather compartment 38 and the guide opening 34 when the plunger is in its depressed position substantially as in FIGURE 2.

In the instant embodiment, the plunger rod 11 is formed to define a sealing plug 39 of relatively enlarged diameter adapted for sealing reception within the cylindrical socket or portion 42 of the collar. The cylindrical lower end portion of the plug 39 defines a cylindrical sealing plug for reception in a socket 44 defined by an upwardly projecting and tapered flexible sealing skirt 45 of the piston 10, and the piston 10 is disposed for a limited extent of axial lost motion on the plunger rod 11.

Normally, the piston or sleeve is proportioned for freely sliding telescoping engagement with the lower end of the plunger rod 11 so that the frictional drag between the piston skirt 12 and the cylinder wall will cause relative movement between the plunger rod and piston for achievement of the valving functions hereinafter described. The spring 25 engages and abuts axially against the plunger rod, by way of its depending discharge valve member 19, and is disengaged from the piston so that the piston receives its drive only from the plunger.

As was earlier mentioned, the piston is essentially in the form of a tubular sleeve having a partition 46 extending radially across its interior and formed with the discharge port 20 for cooperation with the valve body 19, which constitutes a fixed portion of the plunger rod 11. Valve member 19 seats against the partition 46 to close the port 20 in the fully raised position of the plunger P. In the embodiment shown, the valve body or member 19 is carried at the lower end of a grooved or fluted valve stem 47 which extends and is frictionally positioned in the lower end portion of the plunger discharge passage 18. The arrangement is such that, when the valve 19 is unseated by downward pressure on the plunger, liquid is free to pass upwardly through the valve port 20 and through the flutes of the valve stem 47, thence through the remainder of the discharge passage 18 and conventional discharge head 21 for discharge through the orifice 22. In accordance with conventional practice, intermittent finger pressure may be applied to the plunger to depress it on its compression stroke and thereafter to permit its return on the suction stroke by means of the return spring 25.

The pison skirt preferably is of decreasing thickness, or in other words is downwardly tapered toward its lower edge extremity, to lend increased flexibility such as will enable it to maintain sealing engagement with the cylinder wall even when passing over irregularities thereon. In addition, the diameter of the lower end or periphery 12 of the skirt, prior to assembly within the cylinder, norrnally has a somewhat greater diameter than the cylinder so that, upon being received within the cylinder, it is radially compressed and thus exerts a resilient radial pressure against the cylinder. In order to facilitate reception and compression of the piston with the cylinder, the upper end of the cylinder is preferably provided with a downwardly converging funnel-shaped portion 48.

The mid-portion of the plunger spring 25 consists of a series of convolutions of uniform diameter and of usual spiral disposition except for the endmost coils thereof, which preferably are disposed in planes radial to the axis of the cylinder, so that either of them might seat on the annular ledge or seat 49 in the pump chamber. At its upper and lower ends, the spring 25 has relatively reduced diameter extensions 25a and 25b of similar size and configuration to render the spring reversible. One of these, 25a, extends downwardly into the relatively reduced diameter valve cage 50- and terminates in slightly spaced relation from the inlet valve to limit the unseating thereof. The other extension, 25b, extends into the piston skirt 12 .and thrusts axially against valve 19.

The entire upward axial thrust of the spring 25 is accordingly exerted solely upon the hollow plunger rod, the piston normally being coupled to the plunger rod for movement therewith by abutment between its partition 46 and the lower end of the plunger rod 11 on the one hand, and by abutment between said partition and the valve member 19 on the other hand.

The operation of the invention is believed to be apparent. With the pump positioned in a container and maintained in its normally raised position by the spring 25, upward movement of the plunger piston is arrested by sealing engagement of its upper skirt 45 with the conical surface 43 of depending sleeve 41. The thrust of the spring 25 against the valve member 19 is then utilized to resiliently maintain the upwardly directed sealing skirt 45 of the piston in the downwardly diverging annular groove between the skirt 41 and the plug portion 44 of the plunger.

The sealing skirt 45 of the piston is wedged into this groove and radially compressed between the opposing inner and outer walls of the groove to engage both walls with a substantial radial sealing force such as will prevent leakage upwardly between the plunger and collar through the valve opening 18. A secondary seal is defined by the plug 44 received in the opposing cylindrical cavities defined by the sealing skirt 45 and the sleeve 41, respectively. The plug 44 also prevents radial inward collapse of the sealing skirt 45, under the radial wedging pressure arising from its engagement with conical surface 43.

As soon as the plunger is urged downwardly by pressure on the finger piece 24, both the sealing skirt 45 and plug 44 are withdrawn from engagement with the collar 17 so that the breather compartment 38 communicates with the atmosphere through the guide opening 34. Downward movement of the plunger rod 11 will result in lost motion with respect to the piston. This will result in unseating the valve 19 to permit discharge of liquid through the plunger port 20 and discharge passage 18 throughout each downward stroke of the plunger, the inlet valve 15 at this time being maintained seated by liquid pressure.

0n the other hand, at the inception of each upward plunger stroke by action of the spring 25, the discharge valve 19 will seat over the port 20 incident to lost motion between the plunger rod and piston. Suction within the pump chamber will unseat the inlet valve 15 to permit flow of liquid into the pump chamber 13. As the plunger moves to its fully raised position, any liquid within the cylinder above the piston is urged through the open upper end of the cylinder into breather compartment 38, from which it can then drain back into the container, through passage 40 and the spider 32. The spring pressure on the discharge valve 19 will maintain the latter seated to seal the plunger discharge passage 18; and the external seal around the plunger, provided by sealing skirt 45 and its cooperating valve parts, will also be established and resiliently maintained by the spring pressure.

Except as hereinafter described, the parts and mode of operation of the modified embodiment of the invention shown in FIGURE 4 are substantially similar to those of the embodiment above described, and the parts are accordingly designated by reference numerals similar to those in the preceding figures, which numerals are primed with respect to modified parts.

With respect to the embodiment of FIGURES 1, 2 and 3, it will be appreciated that the first and second sealing portions 43 and 45 will function efiiciently to prevent leakage of liquid between the piston 12 and its associated plunger rod 11 as long as the plunger is fully raised. However, the sealing portions 43 and 45 will be disengaged throughout the operative pumping stroke of the plunger. With the structure shown in the preceding figures, if the piston 12 and plunger 11 are so closely interfitted as to preclude leakage of liquids between them, particularly where the liquids have a low viscosity, such close interfitting is likely to result in interference with the valving motion of the piston on the plunger rod.

To afford such a seal which will not unduly interfere with or bind the piston against its valving motion on the plunger rod, the rod itself is provided with an annular recess 61 in its lower end between the external wall of the plunger and its internal bore. The piston 10', in turn, is provided with an upstanding annular skirt 62 projecting upwardly around the inner bore or periphery of the piston from the partition 46' thereof. Preferably, the upstanding skirt 62 is provided adjacent its upper extremity with a radially outwardly directed sealing lip or heading 63 arranged to sealingly engage the inner surface of the outer wall 64 of groove 61. The cylindrical conformation of such wall inner surface will permit free axial reciprocation of the piston member with respect to the plunger rod.

Because of the elastic resiliency of the material from which the piston is formed, its upstanding annular skirt 62 will be radially outwardly expanded by the pressure of liquid within the plunger and will thus be urged into sealing engagement with the wall 64 by the internal liquid pressure.

It will further be noted that the two interengaged sealing elements here referred to, namely the wall 64 and the upstanding skirt 62, are each recessed within cavities of their respective parts such that they are protected from contact with other components when stored in quantity and when handled during production. By such disposition, they are protected against damage such as might arise from contact with other parts or from handling during assembly. Thus, these parts, which are quite thin and which may be quite delicate when employed in small plastic pumps, are so disposed and protected that their scaling functions will remain unimpaired despite such handling and storage.

It will be apparent that the protective cavity within which the sealing surface of the inner wall 64 is housed comprises the groove 61, whereas the cavity which houses the sealing element 62 is defined by the surrounding upwardly projecting skirt 45.

With further reference to the embodiment of FIGURE 4 there are incorporated certain further added features and distinctions over the first embodiment. For instance, in the first embodiment, the uniform internal diameter operative portion of the cylinder is projected upwardly through the container closure and to a location above the spider 32 which secured the cylinder to its supporting flange and encircling wall 26 and 27 respectively. The breather compartment 38 was, therefore, necessary to establish communication between this cylinder and the container interior. However, the breather compartment and spider both are omitted from the simplified modification in FIGURE 4 in which the pilot portion 48' of the cylinder is connected directly to the flange 26' and the wall 27.

The operative uniform diameter pumping portion of the cylinder comprises the pumping chamber 13 which is disposed wholly below the closure cap and communicates with the container through vent openings 51 in the conical pilot portion 48'. At the same time, the inner sleeve 41' of the collar 33' is elongated to extend downwardly into the conically flared pilot portion 48 of the cylinder for cooperation with the piston The extended inner sleeve 41' thus affords a supplemental means for guiding the plunger throughout the large portion of the plunger stroke, though it has sufiicient clearance with the plunger rod to permit the inward passage of air from the atmosphere, or the escape of vapor at pressures above atmospheric throughout the operative stroke of the plunger.

The depending sleeve 41' of the collar further functions to arrest the piston movement at the end of each upward stroke in a position such that the piston skirt 60 remains in the pump chamber 13' in operative sealing engagement with the cylindrical inner wall portion of the chamber 13'. However, a portion, at least, of the lower end of the sleeve 41' terminates in spaced relation from the inner surface of the cylinder to define therein a vent passage 52 which communicates through one Or more of the vent openings 51 with the interior of the container.

It will be noted that the vent openings 51 are placed axially above the pump chamber 51 at a location in the conical pilot portion 48' of the cylinder, the internaldiameter of which substantially exceeds that of the piston so that such portion, and the edge of any such vent opening 51, is never contacted by the piston skirt at any time.

The embodiment of FIGURE-4 further includes a protective overcap 54 for the externally projecting portion of the pump structure. This is for the purpose of preventing inadvertent actuation of the plunger P during shipping and storage as well as for protecting the same against damage. For securing the overcap 54 in its oper- 8 ative position, the collar 33' of the pump assembly has been modified to include an outwardly projecting circular flange 55 having an upstanding cylindrical rim 56. The radially outer face of the rim 56 is formed with circumferentially extending corrugations 57 for cooperation with similar corrugations 58 on the inner face of the generally cylindrical depending skirt of the overcap 54. The lower edge of the overcap skirt will normally bear against the top wall of the container closure cap 31 to transmit axial thrusting forces to the latter. The top wall of the cap 31 will normally be of substantial thickness if formed of plastic material, as illustrated in FIGURE 4, though it may be considerably thinner if formed of sheet metal in accordance with conventional practice.

To adapt the overcap for efficient use with containers having either type of cap, the corrugations 57 and 58 are arranged in series in which the corrugations of each series are uniformly shaped and are relatively equidistantly spaced. The spacing between corrugations in each series 57 and 58 is identical so that the crests of one set of corrugations will fit snugly between the crests of the corrugations of the other series in any of various axial positions of the overcap 54 on the collar 33.

By virtue of this arrangement, the overcap will be retained on the pump in any of various positions of axial adjustment and will be adapted for use with container caps, the top walls of which have varying thicknesses, the uniform axial spacing between the joining of corrugations series 57 and 5S normally amounting to but a small fraction of the thickness of the closure cap top wall.

It is further to be noted that the valve 19 which controls the discharge port 20' of the piston sets against a sealing surface 66 which, in the present embodiment, is provided by the conical inner face of the piston skirt 12. Thus, there is achieved a wedging sealing engagement between the vaive 19 and the surface 60 in which the spring pressure of the plunger spring 25 may be employed at a mechanical advantage.

It is further to be noted that, in the embodiment of FIGURE 4, the sealing relation between the collar 33' and the annular wall 27 of the cylinder structure is supplemented by the addition of a cylindrical sealing surface 65 within the collar 27 which is connected to the somewhat larger diametcr upper portion of the annular wall 27' by a conical camming surface 66. The depending internal sleeve 35' of the collar is provided with a depending sealing skirt 67 of substantially less wall thickness than the rest of the sleeve 35' to achieve a certain degree of flexibility; whereby the radially outward lip 68 at its lower end may conformingly engage and seal against the surface 65. In order to seal radially against the surface 65, the lip 68 may have a somewhat larger external diameter than the surface 65 so that it will be somewhat radially compressed by coaction with the conical camming surface 66 incident to its reception within the surface 65.

Having thus described my invention, I claim:

1. In a liquid dispensing pump of the class which comprises a pump cylinder and means for supporting the cylinder in sealed relation through the outlet of a liquid container, a plunger disposed for reciprocation in the cylinder through the upper end thereof and therewith defining a variable volume pump chamber within the cylinder, the plunger including a piston within said cylinder and a plunger rod on which said piston is slidably disposed, said plunger rod projecting outwardly from the piston through the upper end of the cylinder, said cylinder being provided with a valve controlled inlet port opening into the pump chamber, and said plunger defining a valve controlled dis charge passage from the pump chamber to the atmosphere, the improvement which comprises an annular collar encircling said rod and afiixed to the upper end of the pump cylinder said collar including an upper. wall formed with a guide opening which slidably receives said plunger rod and through which said cylinder normally communicates with the atmosphere, said plunger and said collar having relatively axially opposed valve portions encircling the plunger and disposed for sealing engagement with each other in the fully raised position of the plunger to seal said guide opening, said valve portion of the collar being formed to define a counterbore around and radially spaced from said plunger rod, and said valve portion of the piston comprising an annular upwardly directed flexible skirt encircling the plunger rod for sealing reception in said counterbore, the relatively adjacent surfaces of said counterbore and said skirt being conformed to radially compress said skirt into sealing engagement with the outer surface of said plunger rod as the plunger is moved to its fully raised position.

2. A liquid dispensing pump as defined in claim 1, in which the piston comprises a sleeve-like member of elastomeric material telescopically disposed on the plunger rod, said collar defining a downwardly diverging conical valve seat below and concentric to the guide opening for sealing engagement with the valve portion of the piston, the valve portion of the piston comprising an annular upwardly directed flexible skirt, said plunger rod radially reinforcing said skirt to limit the inward deflection thereof by said conical valve seat.

3. In a liquid dispensing pump as defined in claim 1, the further improvements wherein said piston is of resiliently deformable elastomeric material of sleeve-like configuration, telescopically disposed on the plunger rod for limited axial sliding movement, and cooperating valve portions are carried by the plunger rod and the piston respectively for alternately closing and opening the plunger discharge passage incident to reciprocation of the plunger rod and the frictional engagement between the piston and cylinder, said valve portion of the collar defining a downwardly divergent conical valve seat in said counterbore below said guide opening for radial sealing engagement with the upper end of said piston skirt and for compressing same radially against said plunger rod.

4. In a liquid dispensing pump as defined in claim 2, the further improvements wherein said plunger rod comprises an annular wall depending from its lower end and defining a cylindrical internal sealing surface, said piston having an upstanding elastically expansible skirt telescopically received in said wall in sealing engagement with the internal sealing surface thereof, whereby liquid pressure within said upstanding skirt will urge it into sealing engagement with the said annular wall.

5. In a liquid dispensing pump as defined in claim 4, the further improvement wherein the internal sealing surface of said annular wall and the said upstanding skirt are both housed in cavities within their respective members.

References Cited UNITED STATES PATENTS 3,229,864 1/1966 Roder 222-321 3,257,961 6/ 1966 Schlenker 222-321 3,282,472 11/ 1966 Roder 222-321 ROBERT B. REEVES, Primary Examiner. HADD S. LANE, Assistant Examiner. 

